JPH0519862A - Servo controller - Google Patents

Abstract

PURPOSE:To eliminate position deviation by gain control by a feedforward control part even if the position deviation due to load variation is generated in the servo controller. CONSTITUTION:The servo controller which performs the sine-wave driving of a machine is provided with a variable gain feedforward control part 7A and also provided with a feedforward gain error estimation part 21 which controls the gain of the feedforward control part 7A. This feedforward gain error estimation part 21 estimates the gain error of feedforward from a position command, the amplitude ratio of the position deviation corresponding to it, and a phase difference and outputs it to a feedforward control part 7A. The feedforward control part 7A adjusts the feedforward gain with the gain error estimated by the gain error estimation part 21 so that the position deviation of the control system becomes zero.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a servo control device for driving a machine with a sine wave.

[0002]

2. Description of the Related Art A conventional servo controller having a feedforward control function is constructed as shown in FIG. That is, in FIG. 2, reference numeral 1 denotes a motor / mechanical system. The angle θ and the angular velocity θ ′ are detected from the motor / mechanical system 1, and the angle θ is input to the minus terminal of the subtractor 2 and the angular velocity θ ′ is input to the adder / subtractor minus terminal. To be done. On the other hand, the sine wave position command θr indicating the target position is input to the + terminal of the subtracter 2 in the control system, and the detected angle θ is subtracted from the position command θr to obtain the position deviation “θr−θ”. This position deviation “θr −
“θ” is input to the multiplier 3, multiplied by the position feedback gain Gp, and the multiplication result is input to the + terminal of the adder / subtractor 4.

The position command θr is sent to the feedforward controller 7 in addition to the control system. The feedforward control unit 7 is composed of differentiators 8 and 10 and multipliers 9 and 11. The position command θr input to the feedforward control unit 7 is differentiated by the differentiator 8 to become a speed command θ′r, which is input to the multiplier 9 and multiplied by the speed feedforward gain KVFF to become a speed feedforward value. ..

This speed feedforward value is input to the + terminal of the adder / subtractor 4 in the control system. Therefore, the adder / subtractor 4 adds the velocity feedforward value from the multiplier 9 to the output of the multiplier 3 and subtracts the angular velocity to obtain the velocity deviation, which is output to the multiplier 5. Multiplier 5
Outputs the speed deviation multiplied by the speed feedback gain Gv to the adder 6.

The speed command θ'r differentiated by the differentiator 6 is differentiated by the differentiator 10 to become an acceleration command θ ″ r. This θ ″ r is input to the multiplier 11 and the torque feed is supplied. The forward gain JO is multiplied to obtain the torque feedforward value. This torque feedforward value is input to the adder 6 of the control system and added to the output of the multiplier 5 to form the torque command u, which is input to the motor / mechanical system 1.

[0006]

As described above, in the conventional servo control device, the feedforward gain in the feedforward control unit 7 is fixed, and therefore there is a gain error in the feedforward gain due to load fluctuations and the like. In this case, the position deviation is canceled by feedback, but there is a problem that the deviation cannot be suppressed for a high-speed sine wave command due to the delay of feedback.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a feedforward device capable of remarkably reducing the position deviation by rapidly and automatically adjusting the gain of the feedforward.

[0008]

According to the present invention, in a servo control device for driving a machine in a sine wave, a control system for driving and controlling a controlled machine according to a position command indicating a target position, the position command and a position deviation corresponding thereto. The feed-forward gain error estimator that estimates the feed-forward gain error from the amplitude ratio and the phase difference of and the gain error estimated by this gain error estimator so that the position deviation becomes zero for the control system. And a feedforward control unit for adjusting the feedforward gain.

[0009]

When a position command is given, the control system operates according to this position command to drive the controlled machine. Further, at this time, the feedforward gain error estimation unit operates, and the feedforward gain error, that is, the torque feedforward gain error ΔJ and the speed feedforward gain error is calculated from the position command and the amplitude ratio and phase difference of the position deviation with respect to the position command. Estimate ΔKVFF and output the estimated value to the feedforward control unit. This feedforward control unit adjusts the feedforward gain so that the position deviation becomes zero with respect to the control system based on the gain error estimated by the gain error estimation unit. Even if
By adjusting the gain in the feedforward control unit,
The position deviation can be reduced.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

According to the present invention, in the circuit shown in FIG. 2, a variable gain feedforward control unit 7A is provided in place of the fixed gain feedforward control unit 7.
A feedforward gain error estimation unit 21 that controls the gain of the feedforward control unit 7A is provided. Since other configurations are the same as those of the circuit of FIG. 2, the same reference numerals as those in FIG. The feedforward control unit 7A constitutes a circuit using differentiators 8 and 10 and variable gain multipliers 9a and 11a.

Further, the feedforward gain error estimation unit 21 calculates the torque feedforward gain error from the position command θr and the position deviation “θr−θ” output from the subtracter 2 according to equations (10) and (11) described later. ΔJ and velocity feedforward gain error ΔKVFF are calculated and output. The torque feedforward gain error ΔJ adjusts the torque feedforward gain JO of the multiplier 11a to "JO + ΔJ".
Similarly, the speed feedforward gain error ΔKVFF adjusts the speed feedforward gain KVFF of the multiplier 9a to “KVFF + ΔKVFF”. By the above automatic adjustment, the position deviation “θr−θ” is changed so as to approach zero. Next, the operation of the above embodiment will be described. The system in the case of using the fixed gain feedforward controller 7 shown in FIG. 2 is expressed by the following equations (1) and (2).

That is, the torque command is u, the angle is θ, the position command is θr, the moment of inertia is J, the motor time constant is T, the speed feedback gain is Gv, the position feedback gain is Gp, and the speed feedforward gain is K.
Assuming that VFF and torque feedforward gain are JO, the equation of motion of the motor / mechanical system 1 is expressed by the equation (1), and the equation of the torque command u is expressed by the equation (2). J θ ″ = u / (1 + TS) (1) u = JO θ ″ r + Gv {KVFF θ′r −θ ′ + Gp (θr −θ)} (2) The position is calculated by the above equations (1) and (2). The transfer function from the command θr to the position deviation “θr −θ” is given by equation (3).

[0014]

[Equation 1] However, torque feedforward gain error ΔJ = J−JO (4) Speed feedforward gain error KVFF = 1−KVFF (5) With the transfer function of the equation (3), the position command θr has an amplitude A,
As a sine wave of constant frequency ω,

[0015]

[Equation 2] If is added, the positional deviation “θr−θ” is given by equation (7).

[0016]

[Equation 3] However, ΔA and Δθ are the amplitude and phase difference of the position deviation, respectively.
Equations (8) and (9) are obtained.

[0017]

[Equation 4] By changing the above equations (8) and (9), from ΔA and Δθ to ΔJ,
Derivation of the equation for obtaining ΔKVFF yields (10), (11)
It becomes an expression.

[0018]

[Equation 5]

Using the above equations (10) and (11), the torque feedforward gain error Δ is calculated from the position command amplitude A, the frequency ω, the position deviation amplitude ΔA, and the phase difference Δθ.
J, velocity feedforward gain error ΔKVFF can be obtained. This feedforward gain error Δ
Using J and ΔKVFF, the feedforward gain JO,
By automatically adjusting KVFF as in equations (12) and (13), the position deviation "θr-
θ ”can be zero. JO + ΔJ → JO… (12) KVFF + ΔKVFF → KVFF… (13)

[0020]

As described above in detail, according to the present invention, the position deviation "θr-θ" is set to zero in the feedforward gain error estimator 21 from the position command and the amplitude ratio and phase difference of the position deviation corresponding thereto. Thus, the torque feedforward gain error ΔJ and the speed feedforward gain error ΔKVFF are calculated, and the torque feedforward gain JO and the speed feedforward gain KVFF are adjusted accordingly. Therefore, even if the position deviation “θr −θ” occurs due to load fluctuations, etc., the position deviation “θr −θ” is automatically adjusted by the feedforward gains JO and KVFF in the multipliers 11 and 9 of the feedforward control unit 7A. It can be zero.

[Brief description of drawings]

FIG. 1 is a block diagram of a servo control device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional servo control device.

[Explanation of symbols]

1 ... Motor / mechanical system, 2 ... Subtractor, 3 ... Multiplier (position feedback gain Gp), 4 ... Adder / subtractor, 5 ... Multiplier (speed feedback gain Gv), 6 ... Adder, 7,
7A ... Feedforward control unit, 8, 10 ... Differentiator,
9: Multiplier (speed feed forward gain KVFF),
11 ... Multiplier (torque feed forward gain JO
), 21 ... Feedforward gain error estimation unit.

Claims (1)

Claim: What is claimed is: 1. A servo control device for driving a machine in a sine wave, a control system for driving and controlling a controlled machine according to a position command indicating a target position, and the position command and the amplitude of a position deviation relative to the control command. The feedforward gain error estimator that estimates the feedforward gain error from the ratio and phase difference, and the gain error estimated by the gain error estimator are used to adjust the feedforward so that the position deviation becomes zero with respect to the control system. A servo control device comprising a feedforward control unit for adjusting a gain.